1. Field of the Invention
The present invention relates generally to cutting and grinding abrasive tools. In particular the present invention relates to a grinding tool such as a disc or wheel or brick having abrasive segments, preferably superabrasive segments, affixed thereto and a method for making the same.
2. Description of the Related Art
Certain types of workpieces (plastic and glass lenses, stone, concrete, and ceramic for example) can be advantageously shaped using grinding tools, such as a wheel or disc, which have an abrasive work surface, particularly a superabrasive work surface, a superabrasive surface also being an abrasive surface but having a higher abrasivity. Many other substances can also benefit from this type of shaping or grinding by a superabrasive work surface. The work surface of the grinding wheel is commonly made up of one or both planar disc surfaces on each face of the grinding wheel. The work surface usually includes particles of super hard or abrasive material, such as diamond, cubic boron nitride, or boron suboxide surrounded by a bond material and/or embedded in a metal matrix. It is these hard particles that primarily act to cut or grind a workpiece as it is brought into contact with a rotating work surface of the grinding tool.
Grinding wheels and discs including a work surface having a homogeneous concentration of hard particles over the entire work surface are known in the art. Also known are grinding wheels and discs including work surfaces having regions of higher concentrations of hard particles, regions of lower concentrations of hard particles, and regions having no hard particles.
Because grinding characteristics of a grinding tool, e.g. disc or wheel, such as grinding rate and tool wear rate can be varied by varying the area of grinding surface (the surface of the tool which acts primarily to grind a workpiece) on the grinding tool, it is advantageous to be able to vary the area of grinding surface on a grinding tool. However, the grinding tools discussed above are formed such that the grinding surfaces have a moderate concentration of hard particles. As such, relatively large areas of the work surface of the tools must make up the grinding surface and precise, variation of the area of the grinding surface of the tool can be problematic. Further, the cost of fabricating a grinding tool having a relatively large area of the work surface made up of grinding surface can be relatively high.
Accordingly, there is a continuing need for improved grinding tools. In particular, there is a need to be able to vary the area of the grinding surface of a grinding tool to allow the tool to be able to achieve relatively high grinding speeds while retaining a relatively long life. Also, there is a need to be able to reduce the portion of a work surface of a grinding tool which has abrasive particles so that the tool can be efficiently manufactured.